In recent years, with increasing environmental consciousness, more and more products are designed in views of energy conservation and carbon reduction policy. Consequently, government organizations, enterprises, schools or families pay much attention to the reduction of the frequency and time period of using the air conditioners. For maintaining air circulation and increasing space utilization, a variety of new fans and recirculation fans are introduced into the market.
For most fans, a motor is employed to drive rotation of the fan blades and the wind-guiding device. The rotation of the fan blades may produce airflow. The rotation of the wind-guiding device may blow the airflow to different regions. Consequently, the convection within the indoor construction site will be enhanced and the indoor temperature can be controlled.
For increasing the space utilization, the mainstream of the indoor recirculation fan is for example an embedded-type recirculation fan. However, due to the spatial and position limitation, the performance of such recirculation fan is usually unsatisfied. In addition, if the amount of the airflow required for indoor convection is increased, the recirculation fan should have a longer and larger fan blade. Correspondingly, a large-power and large-size motor is used to provide sufficient torque to rotate the recirculation fan. For complying with the large-size motor, the volume of the fan should be largely increased. Under this circumstance, a lot of space is occupied. Moreover, since the wind-guiding device of the current recirculation fan is synchronously driven by the motor, the rotating speed is possibly too fast and the airflow is centralized. In other words, since the airflow fails to be effectively spread to various regions, the air-circulating efficiency is deteriorated. In addition, since the overall power consumption is largely increased, it is difficult to achieve the energy conservation and carbon reduction purpose. In other words, the process of deploying the conventional recirculation fan is complicated and the layout cost is increased.